It has previously been proposed, see the German Patent Disclosure Document DE-OS 32 48 178, Schneider, to image a form cylinder by a thermo transfer process. A thermo transfer foil is carried adjacent the cylinder to be imaged, which is coated at the side facing the form cylinder with a thermo or electro-thermosensitive material. A recording head, located at the back side of the film, is selectively, for example digitally energized to melt elementary particles from the thermosensitive film and transfer these particles on the form cylinder, where they will adhere or bond to the surface thereof.
The arrangement appears practicable from a theoretical point of view; in actual practice, however, it has been found that the energy requirements to obtain sufficient transfer of material and adhesion is very high; as described in the patent, the surface of the form cylinder may be aluminum which is an excellent heat conductor, so that heat transferred thereto is rapidly conducted away, placing high energy demands on the recording head.